Dynamic produced water treatment apparatus and system

ABSTRACT

An automated produced water treatment system that injects ozone or an ozone-oxygen mixture upstream of produced water separators, with the dose rate changing dynamically as the produced water quality changes, as determined by continuous monitoring of the produced water quality by a plurality of sensors that detect water quality parameters in real time. The system may operate as a “slipstream” injection system, that draws a portion of produced water from the produced water pipeline and injects ozone or an ozone-oxygen mixture back into the pipeline with disrupting or slowing normal operations. Disinfectants or other additives may also be injected. The treatment system may be wholly or partially contained in mobile containers or trailers, for on-the-fly use in existing produced water treatment facilities.

This application is a continuation of U.S. patent application Ser. No.16/246,646, filed Jan. 14, 2019, and a continuation of PCT PatentApplication No. PCT/US19/13431, filed Jan. 14, 2019, both of which claimbenefit of and priority to U.S. Provisional Applications No. 62/749,150,filed Oct. 23, 2018, No. 62/731,748, filed Sep. 14, 2018, and No.62/617,258, filed Jan. 14, 2018. U.S. patent application Ser. No.16/246,646, PCT Patent Application No. PCT/US19/13431, and U.S.Provisional Applications Nos. 62/749,150, 62/731,748, and 62/617,258 areincorporated herein in their entireties by specific reference for allpurposes.

FIELD OF INVENTION

This invention relates to an apparatus and system for automatically anddynamically treated produced water from oil and gas productionoperations.

BACKGROUND OF THE INVENTION

A variety of oil and gas operations generate large volumes of watermixed with hydrocarbons and various contaminants, generally referred toin the industry as “produced water.” Most produced water is contaminatedwith inorganic salts, metals, organic compounds, and other materials,such as emulsifiers or other agents that may be injected for varioustypes of enhanced recovery operations. Typical hydrocarbons in producedwater include semivolatile organic compounds (“SVOCs”) and volatileorganic compounds (“VOCs”). In most operations, produced water istreated by a variety of means to separate hydrocarbons from the fluidstream, and remove or treat contaminants before ultimate disposal.Examples of systems and methods for treating produced water aredescribed in Sullivan, et al., US 2009/0101572, Ikebe, et al., US2010/0264068, and Folkvang, US 2014/0346118, all of which areincorporated herein in their entireties by specific reference for allpurposes.

SUMMARY OF THE INVENTION

In various exemplary embodiments, the present invention comprises anautomated treatment system that injects ozone or an ozone-oxygen mixtureupstream of the separators, with the dose rate changing dynamically asthe produced water quality changes (as determined by continuousmonitoring of the produced water quality by a plurality of sensors thatdetect water quality parameters in real time). In several embodiments,the system may operate as a “slipstream” injection system, that draws aportion of produced water from the produced water pipeline and injectsozone or an ozone-oxygen mixture back into the pipeline with disruptingor slowing normal operations. Disinfectants or other additives may alsobe injected. The ozone is consumed rapidly by bacteria, iron, sulfidesand other reducers in the produced water stream, while the oxygenbubbles in the produced water provides an Induced Gas Flotation (IGF)effect in the downstream separators. The IGF effect clarifies the waterby removing suspended matter in the produced water, such as oil orsolids. The oxygen bubbles provide lift, floats lighter solids, andimproves the oil/water separation process.

In the ozone generation process, oxygen is separated from ambient air,with the remaining “reject gas” typically vented to the atmosphere inprior art operations. In the present process, the reject gas instead isdirected to the separation tanks, where it is used as a blanket gas inthe tanks. The reject gas comprises mostly nitrogen and thus is inert,and is used as a gas phase maintained above the liquid (i.e., producedwater) in the separation tanks or other vessels to protect the liquidfrom air contamination and to reduce the hazard of explosion or fire.

Some or all of the reject gas (i.e., in conjunction with, or as analternative to, the use of the reject gas as a blanket gas) may also beinjected into the produced water or fluid stream using a nano-bubblediffuser prior to disposal in an injection well. The nano-bubblediffuser introduces the inert gas (mostly nitrogen) into the producedwater in the form of micro- or nano-bubbles, which provide frictionreduction in the fluid, and reduces the injection/disposal well pumppressure.

Various combined systems may introduce ozone/oxygen just prior toinjection for “on-the-fly” disinfection and treatment, while alsoproviding friction reduction benefits, in combination with a secondarysystem that introduces nitrogen or nitrogen-rich gas in the form ofmicro- and/or nano-bubbles (through nano-bubble diffusers) to increaseor optimize friction reduction. The nitrogen nano-bubble delivery systemalso may be used independently as an “on-the-fly” stand-alone frictionreduction system. A nitrogen concentrator also may be used to addnitrogen or increase the nitrogen concentration in a gas prior toforming the bubbles.

DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a diagram of an exemplary embodiment of the presentinvention.

FIG. 2 shows a diagram of another exemplary embodiment of the presentinvention.

FIG. 3 shows a diagram of another embodiment of the present inventionwith reject gas injection.

FIGS. 4-10 show exterior and interior views of single and dual unitembodiments of the present invention.

FIG. 11 shows an example of a system status display screen.

FIG. 12 shows a top view of a single unit embodiment of the presentsystem.

FIGS. 13-15 show top views of a dual unit embodiment of the presentsystem.

FIGS. 16-18 show examples of combined systems with friction reduction.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Produced water originates at the wellhead, and then typically travelsvia pipeline 10 to tank batteries, where held for a gathering system forprocessing and treatment. In general, oil or other hydrocarbons areseparated and collected, and the remaining wastewater is directed to aninjection or disposal well 30. One of the most common oil/waterseparation systems use one or more “gun barrel” separation tanks 20, asseen in FIG. 1.

As the produced water travels from the wellhead and through thegathering system, it is subjected to various treatments or processes.For example, the produced water receives injections of chemicals at ornear the well head, either in batch or continuous treatments. As theproduced water slows down in the gun barrel separators 20, bacteria canaccumulate and hydrogen sulfide can form. To counter this, biocidalagents typically are added upstream of the gun barrel separators.Chemical biocides generally are added at a predetermined, constant doserate, but as produced water quality changes, this constant dose ratebecomes ineffective.

In several embodiments, the present invention comprises an automatedtreatment system 2 that injects ozone or an ozone-oxygen mixture 40upstream of the separators, with the dose rate changing dynamically asthe produced water quality changes (as determined by continuousmonitoring of the produced water quality). While ozone-oxygen may beadded directly, in a preferred embodiment, as seen in FIG. 1, the systemmay operate as a “slipstream” injection system 40, that draws a portionof produced water from the produced water pipeline 10 and injects ozoneor an ozone-oxygen mixture into this drawn-off portion, which is thenintroduced back into the main produced water pipeline 10 withoutdisrupting or slowing normal operations. Disinfectants or otheradditives may also be injected into the drawn-off portion (or directlyinto the main produced water pipeline).

The ozone is consumed rapidly by bacteria, iron, sulfides and otherreducers in the produced water stream, while the oxygen bubbles in theproduced water provides an Induced Gas Flotation (IGF) effect in thedownstream separators. The IGF effect clarifies the water by removingsuspended matter in the produced water, such as oil or solids. Theoxygen bubbles adhere to suspended matter, provide lift, floats lightersolids to the surface of the water, and improves the oil/waterseparation process.

In the ozone generation process, oxygen is separated from ambient air,with the remaining “reject gas” (i.e., the oxygen-depleted ambient airleft after separation) typically vented to the atmosphere in prior artoperations. In several embodiments of the present process, this rejectgas instead is directed to the separation tank(s) 20, where it is usedas a blanket gas 50 in the tanks, as seen in FIG. 2. This reject gascomprises mostly nitrogen and thus is inert, and is used as a gas phasemaintained above the liquid (i.e., the produced water being treated) inthe separation tanks or other vessels to protect the liquid from aircontamination and to reduce the hazard of explosion or fire.

In yet a further embodiment, as seen in FIG. 3, some or all of thereject gas (i.e., in conjunction with, or as an alternative to, the useof the reject gas as a blanket gas 50) may also be injected 60 into theproduced water or fluid stream using a nano-bubble diffuser prior todisposal in the injection well 30. The nano-bubble diffuser introducesthe inert gas (mostly nitrogen) into the produced water in the form ofmicro- or nano-bubbles, which provide friction reduction in the fluidbeing injected into the injection/disposal well, and reduces theinjection/disposal well pump pressure.

While the system may be a permanently installed component of a producedwater treatment facility, in various alternative embodiments, as seen inFIGS. 4-10, the system is contained in one or more portable, movablecontainers or trailers 110 with ventilation 112, such as a modifiedshipping container or wheeled trailer. One or more doors 120 allow useraccess to the interior, which contains the components of the system.

The container/trailer 110 is moved to a desired location next to asection of the produced water pipeline, and fluid connection is made.The present system can thus be easily retro-fitted to existing producedwater treatment facilities, removed when operations are terminated, ormoved from location to location as needed. The system is fully automaticonce installed, monitoring water quality and adjusting disinfectant andoxidation dosages automatically as water quality changes, and can bemonitored and operated remotely, using a remote computer or mobilecomputing device (e.g., cell phone, tablet) (an example of a systemmonitoring display 122 is shown in FIG. 11).

FIG. 12 shows a top view of a schematic diagram of an exemplaryinsulated container 110 30 feet long and 7.5 feet wide with double doors110 at one or both ends. The air/water handling system (e.g., aircompressor, chiller, CDA) and water processing systems (O2 concentrator,O2 tank, ozone tank, injection system) are both contained in the sameunit, and may be separated by an insulated panel 130 which also may havea door. The system in this configuration has a processing capacity of15,000 BPD (barrels per day). The interior comprises power supplyconnections, programmable logic controller (PLC), air compressor,compressed/clean dry air package, oxygen concentrator, oxygen gas tank,chilling unit, ozone generator, air conditioning unit, transformer,quality testing unit, and fluid connections and pumps (as also seen inFIGS. 8-10). On one side of the unit is the injection and water quality“slipstream” piping 160 with pump(s) 162, which may be contained in orsuspended above a spill containment tank, pool, or pit. Some of theslipstream piping may or may not enter the interior of the unit,although as shown, the slipstream piping is outside and adjacentthereto.

FIGS. 13-15 shows a top view of dual container units 110 a, 110 b (FIG.13 shows a view of both units, FIG. 14 shows a close-up view of the“remote” air/water handling system unit not directly connected to theslipstream piping, and FIG. 15 shows a close-up view of the waterprocessing unit with the slipstream piping), each 20 feet long, with aprocessing capacity of 30,000 BPD. Several system components are doubled(e.g., two chillers, two air compressors, two ozone tanks, two 02concentrators, and so on) for greater capacity, and the air/waterhandling system and water processing system are separately installed inrespective container units as shown. Piping and conduits 114 extendbetween the units (e.g., A/C power conduits/cables, PLC communicationconduits/cables, cooling water pipes, compressed air pipes).

While the figures show a side-by-side dual configuration, otherconfigurations with two or more container units are possible, and arewithin the scope of this invention. The container units may be ofvarious sizes, and the components therein may vary in placement and sizefrom the figures.

In several embodiment, combined systems may be used to introduceozone/oxygen (as described above) prior to or just prior to injectionfor “on-the-fly” disinfection and treatment, while also providingfriction reduction benefits, in combination with a secondary nitrogennano-bubble system that introduces nitrogen or nitrogen-rich gas in theform of micro- and/or nano-bubbles (through nano-bubble diffusers) toincrease or optimize friction reduction. The nitrogen nano-bubbledeliver system may be contained in a container(s) or trailer(s) in thesame manner as described above for oxygen/ozone systems. The nitrogennano-bubble delivery system also may be used independently (i.e.,without the ozone/oxygen system) as an “on-the-fly” stand-alone frictionreduction system. A nitrogen concentrator also may be used to addnitrogen or increase the nitrogen concentration in a gas prior toforming the bubbles.

FIG. 16 shows two examples of optional placement for a nitrogennano-bubble delivery system 200 a, b at an oil/gas produced water (e.g.,salt water) disposal facility. As seen, the system may be located justprior to 200 a injection in the disposal well, or further upstream, suchas prior to 200 b treatment in a desander tank and gun barrel tanks (asdescribed above). FIG. 17 shows similar options for fracking watertreatment (e.g., typically prior to 200 c or after 200 d storage in thefrac water tanks).

FIG. 18 shows a schematic of a nitrogen nano-bubble delivery manifold220. A portion of produced water is drawn off, passed through strainers222, and injected with nitrogen nano-bubbles 224, then mixed 226 backwith the produced water. The treated water 230 then flows downstream forfurther treatment (if any) and injection. Flow meters are used tomonitor fluid flow and control the introduction rates of nitrogennano-bubbles.

Thus, it should be understood that the embodiments and examplesdescribed herein have been chosen and described in order to bestillustrate the principles of the invention and its practicalapplications to thereby enable one of ordinary skill in the art to bestutilize the invention in various embodiments and with variousmodifications as are suited for particular uses contemplated. Eventhough specific embodiments of this invention have been described, theyare not to be taken as exhaustive. There are several variations thatwill be apparent to those skilled in the art.

What is claimed is:
 1. A fluid treatment system configured to treat afluid stream, comprising: a fluid injection or disposal well; one ormore fluid treatment tanks, wherein the one or more fluid treatmenttanks comprise at least one separator; one or more downstream pipesconnecting the one or more water treatment tanks with the fluidinjection or disposal well; upstream pipes in fluid connection with theone or more water treatment tanks; and an ozone injection systemcomprising an ozone generator and an injector configured to inject ozonegas or an ozone-oxygen mixture gas into the fluid stream prior to thefluid stream reaching the fluid injection or disposal well; wherein theozone injection system produces oxygen-depleted inert reject gas in theprocess of producing oxygen and/or ozone; further wherein theoxygen-depleted inert reject gas is directed to the at least oneseparator as blanket gas.
 2. The system of claim 1, wherein the ozoneinjection system injects the ozone gas or ozone-oxygen mixture gasupstream of the one or more fluid treatment tanks.
 3. The system ofclaim 1, wherein the ozone injection system is a slipstream injectionsystem configured to draw off a portion of the produced fluid stream forozone gas or ozone-oxygen mixture gas injection with subsequentre-introduction of that portion of the produced fluid stream to theproduced fluid stream.
 4. The system of claim 1, wherein the ozoneinjection system injects a dose rate of ozone gas or ozone-oxygenmixture gas that varies over time.
 5. The system of claim 4, wherein thedose rate varies dynamically as the quality of the fluid stream changesbased upon continuous monitoring of the fluid stream quality.
 6. Thesystem of claim 1, wherein the ozone gas or an ozone-oxygen mixture gasis injected as nano-bubbles or micro-bubbles.
 7. The system of claim 1,wherein the ozone injection system is contained in whole or in part in amoveable container or trailer.
 8. The system of claim 1, wherein thefluid stream is produced water from oil or gas wells, and/or fracturingfluid for a hydrocarbon fracturing operation.
 9. The system of claim 1,further comprising a nitrogen nano-bubble delivery system, configured toinject nitrogen or nitrogen-rich gas into the fluid stream.
 10. Thesystem of claim 1, wherein nitrogen or nitrogen-rich gas is injecteddownstream of the one or more fluid treatment tanks.